I have installed a wood/coal burning cast iron insert and mantlepiec
and have filled the space behind the insert with hardcore. I have bee
told, in the interest of safety, to skim the top of the hardcore wit
fireproof cement. All I can find is 2kg tubs of fire cement fro
Wickes which I have used to do some repointing inside the fireplace
Although relatively inexpensive, I would need quite a few tubs to put
screed over the hardcore. Is there a fireproof cement that can b
bought in larger quantities or is there something I can add to norma
cement? If not can I render with a sharp sand/cement mix then skim ove
with the Wickes fire cement? I have visited most of the builder
merchants and fireplace suppliers in Bedford but have been greeted wit
Any advice would be greatly appreciated
On Wed, 14 Jun 2006 16:59:18 +0100, Chris Learmouth
Talk to Purimachos in Bristol. Helpful and cheap, if you're avoiding the
Usually the face is a solid slab that you buy ready-made, the infill is
vermiculite and you only need a small tub of fire cement to fill the
gaps. There are also DIY recipes (concrete, but with vermiculite as
aggregate) if you need to cast something monstrous.
The rubble infill is purely to disperse heat away from the cast iron
fireplace. This help to protect the cast iron and prevent possible
cracking. The screed is not too critical to the performance (IMHO) but
will help to prevent moisture ingress, and also soot falling behind the
insert when the chimney is swept. I would go for a weak sand cement
mix, and if you wanted to be particularly fussy then some lime might be
a good idea.
NewArk Traditional Kitchens (01556 690544)
can't remember. 2:1 ? 3:1 OPC & building sand. there may be microcracks
in the flaunching but it all gets sooted up quite quickly. I also used a slurry
of vermiculite & cement to backfill the firebacks.
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Chris Learmouth
From another place.
How to make fire cement...
A good heat insulation material can be made either from mica or
Expanded mica granuls are sold as a soil adiditve to keep the soil free
drained, as isulation as is pearlite which is white beads of mineral.
Expanded mica is a better insilator whilst pearlite probably has the
advantage of highte compressive strength and may incandess better than
You can make any shape you with from either material by mixing enough
with the matereial to make it damp but NOT WET. You can then dust the
mix with 'high alumina' cement, then when throroughly coated pack into
moulds of the correct shape. You must not use ordinary cement as it
not stand the heat.
Alternativly you can use sodium silicate, or commonly it used to be
'water glass'. You mix the sodium silicate with water and then use it
mix in with your agregate (the insulation). It sets to a glass like
material to bind the insulation together. The one problem is with it is
that it takes time to set, the two advantages are that it does not alter
reflective qualities of the agregate by coating it with a grey or black
cement, instead it is galss clear so the mica chips or the white
still reflect heat and the gloss surface adds to this. At very high
temperatures the glass softens so becomes a little plastic. The great
advantage is that the 'stock' of sodium silicate not used will last for
donkey's years where the cement will go off and probably have to be
purchased in 20kg bags.
Sodium silicate sets by absorbing carbon dioxide either from the air as
dries or by blowing carbon dioxide through the material. Placing the
moulded material after sufficient drying to get it to hold up, in a
dioxide rich poly bag etc will speed up the curing.
Using methods like this you can make and re-make refractory and
materials from broken fire bricks. fired expanded clay pebbles and all
to suit your needs.
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